1. Soveltava kurssi Seija Valtonen
Moderni fysiikka
Soveltava kurssi
Seija Valtonen

2. Levels of Understanding I Descriptive Understanding
What do Physicists mean by “We understand”? “The Particle Garden” by Gordon Kane
Levels of Understanding
I Descriptive Understanding
II Input and mechanism Understanding
III Why Understanding
Mothofela
May-19
Hello everybody!!

3. Videocassette recorder
I We can do everything that it is capable of, by experimentation, no documents came with it
II Can repair it without outside help and parts
III Can make it from raw materials without outside help
May-19
Hello everybody!!

4. I. Descriptive Understanding
Newton
Motion and gravitation
Took some inputs and described the motion of the objects
Particle physics
Standard theory
Constituents
Forces
Rules
May-19
Hello everybody!!

5. 3. The rules Einstein’s special relativity The quantum theory
The modern form of the rules
Since the 1920s the rules for calculating have not changed in principle,
tremendous improvement in understanding how to use them.
May-19
Hello everybody!!

6. II. Input and Mechanism Understanding
Requires that
To recognize the mechanism how things work
Knowing the solution of the equations
No masses, constants or parameters be inputs,
they must be derivable from the theory
May-19
Hello everybody!!

7. Newton’s law of gravitation
A field is established by every massive body
The field configuration propagates out from the body at the speed of light
Any other body feels the field and is attracted
What causes the attraction?
The notion of a field
Faraday
Maxwell
Einstein
May-19
Hello everybody!!

8. Atomic physics and quantum theory
We are taught that atoms are understood, but
Why the force that bounds the atom is what it is?
Why the proton and electron has the same magnitude of electric charge?
Why the masses are what they are?
Etc.
May-19
Hello everybody!!

9. Standard Theory
The mathematical form of each force can be derived from the rules once it’s guessed that the force exists.
The existance of a new kind of force is required if a new type of charge is discovered.
No progress in deriving the values of the masses until this.
May-19
Hello everybody!!

10. The Standard Theory 6 quark masses: u, d, c, s, t, b 6 lepton masses:
Electron, muon, tau and the neutrinos
3 kinds of charge
Electric, color, weak
Newton’s gravitational constant G
Planck’s quantum unit h
Speed of light c
Nearly 20 quantities in all
May-19
Hello everybody!!

11. h and c Quantum theory The energy levels of atoms are quantized.
The spacing between the levels is determined by Planck’s constant, h.
Special relativity
The basic laws of nature are the same in any non-accelerating coordinates
2. The speed of light has the same value under all conditions, c
May-19
Hello everybody!!

12. Mechanism understanding is braking the symmetry of the equations
The standard theory equations are symmetric in many ways.
The world is described by a solution that is not symmetric.
Spontaneous symmetrybreaking - why?
May-19
Hello everybody!!

13. III Why Understanding in Particle Physics
A derivation of the existence of e.g. electron, muon and tau leptons?
The values of their masses?
Why 3 leptons, that differ only in mass?
What is electric charge?
Why the forces are the ones we know?
Much more
May-19
Hello everybody!!

14. The mere existence of a problem is no proof of the existence of a solution
Why Understanding in particle physics is a major research activity today.
“Theory of everything”
The glimpses so far of how nature works have shown an austere beauty.
Made by God, who has the keys of life and death
We can’t do even the least, to continue our life –
or the life of our beloved ones